The field of this invention generally includes steam traps, and in particular, steam traps designed to operate quietly. The high fluid velocity of flash steam and condensate flowing past the valve seat of the prior art steam traps tends to generate high noise levels and to cause valve seat erosion including undercutting. The valve seat erosion causes the operation of the steam traps to gradually deteriorate. In some applications the noisy operation of prior art steam traps is very undesirable. Prior art quiet throttling elements have been successfully developed for steam valves and have substantially reduced the noise and erosion problem by greatly decreasing the velocity with which the steam flows through the valve. These throttling elements contain large numbers of very small passages through which the fluid flows. The size of each passage is small enough to reduce pressure by frictional loses and to thereby limit the velocity of fluid flow through it, while the number of passages is large enough to give the throttling element the required flow capacity. Valves with these quiet throttling elements are opened and closed by blocking or unblocking the entrances to these passageways. This type of valve action requires that the valve closing element move a greater distance than is required in standard valves and traps because the passage entrances are stacked one upon the other. The operating force required to move a valve closing element through the quiet throttling element is very high because of sliding friction and unbalanced pressure forces around the valve closing element. For this reason, operating forces in a quiet throttling element are normally higher than those in steam traps.
Examples of prior art steam traps and pressure operated valves are generally shown in U.S. Pat. Nos. 2,051,732; 2,127,649; 2,808,068; 2,936,772; 3,018,023; 3,514,074; 3,776,278; and 4,004,604.
Accordingly, one objective of this invention is to use a quiet throttling element in a steam trap to reduce the amount of throttling noise produced by the steam trap.
Another objective of this invention is to produce a steam trap wherein the closing element moves with a high operating force.
A further objective of this invention is to provide a steam trap which will not suffer valve seat degradation and will thus continue to reliably remove the condensate from a steam line while allowing very little steam to escape from the line.